The present invention pertains to a roll changer for a web-treating or -processing machine, which is set up for a roll change during the stoppage of the roll changer. The present invention also pertains to an automatic roll change in such a machine, in which a web to be replaced is pulled into the machine, but is not in production.
Web-fed printing presses, which are preferred examples of web-treating machines in the sense of the present invention, usually have roll changers which are able to perform a so-called flying roll change. During a flying roll change, a reserve web is joined fully automatically with a working web being wound off from a working roll in the roll changer during running production and is connected to the working web. The reserve web is wound off in the roll changer from a reserve roll. The working web is cut off, and the old working roll is removed from the roll changer either likewise fully automatically or manually and replaced with a new reserve roll. The reserve web attached to the working web is the new working web.
Even though roll changers that are set up for flying roll change are the standard at least in large newspaper rotary printing presses, such a roll change causes problems during the stoppage of the roll changer. In particular, no roll changers are known which are set up for both flying roll change and for fully automatic roll change during the stoppage of the roll changer.
Therefore, the object of the present invention is to make possible automatic roll change during the stoppage of the roll changer, preferably in a roll changer with which flying roll change can be performed.
The present invention is based on a roll changer for a web-treating or -processing machine, which is set up for unwinding a working web to be treated from a working roll, for joining a reserve web to the working web and for connecting the two webs to one another. A preferred example of a web-treating machine is a web-fed rotary printing press, preferably an offset printing press for newspaper printing, especially for printing large editions of newspapers. However, the machine may also be a web-treating or -processing machine for plastics or metals and, in principle, for any web-shaped material, e.g., a plastic film, a metal foil, but especially preferably paper. The web that has already been pulled into the machine and is to be replaced with the reserve web, e.g., after it had been used up, is called the working web in the sense of the present invention.
The roll changer has a first mount for the working roll and a second mount for the reserve roll. The mounts are movable in the roll changer preferably such that they can be moved alternatingly into a working position and into a changing position. The working position advantageously also forms a joining position, which is a bonding position in the case of joining by bonding. The mounts are preferably formed by roll arms, which can be alternatingly pivoted into the working position and into the changing position. The roll changer comprises, furthermore, a connecting means for connecting the reserve web to the working web. The connecting means is preferably designed as a bonding means in order to establish a bonded connection between the working web and the reserve web. This is the currently common connection technique for paper webs in web-fed rotary printing. However, the connecting means may also be formed by a welding means in the case of machines for treating or processing plastic films as well as in machines for treating or processing metal webs. However, other suitable connection techniques shall not be excluded, either, not even for paper webs.
The roll changer comprises, furthermore, a holding means, which is arranged behind the connecting means in the direction of feed of the working web, i.e., downstream of the connecting means along the web. The holding means is designed such that it can fix, preferably completely block the working web in relation to the direction of feed. The fixation preferably takes place exclusively by frictional engagement, especially preferably by clamping the working web.
Finally, the roll changer comprises a pulling means for the working web. The pulling means is arranged in the path of the web between the connecting means and the holding means and is set up or designed such that it can pull the working web from the working roll. The pulling off from the working roll takes place either entirely without support by a motor or with support by a motor or even against a braking force, which may be generated by a drive motor or an additional brake. In any case, an advantageous web tension is generated and maintained during the pulling off by means of the pulling means, optionally in cooperation with a rotating drive of the working roll or a brake for the working roll. Even though the pulling means may be a pulling means with which the web is also fed during running production, the web is preferably fed by means of the pulling means only during the stoppage of the roll changer by an amount that must, of course, be large enough to be able to establish the connection of the reserve web to the working web and to perform the automatic roll change with the working web fixed. If the pulling means also feeds the web during running production, this preferably takes place only temporarily.
An especially elegant solution is the use of a tensioning means as the pulling means, which is used to compensate variations in the web tension during the running production of the machine. Prior-art web tensioning means, e.g., pivotably or linearly movably mounted dancing rollers and equivalent roll means, around which the web is wrapped and which regulate the web tension due to their own movement at right angles to their longitudinal axis by changing the length of the path of the web, are suitable for this. The tensioning element wrapped around by the web, a cylindrical body in the case of a roller or optionally also only a simple rod or the plurality of cylindrical bodies in the case of a roll means, is mounted movably at right angles to its longitudinal axis against the force of elasticity of a restoring element. In the variant of a pulling means according to the present invention, the tensioning element is, furthermore, coupled with a drive bringing about this transverse movement. The drive may be, e.g., an electric motor or a fluid drive, especially a piston-and-cylinder unit. Such a pulling means known from tensioning means may also be used only as a pulling means and does not have to be used as a tensioning means. It is consequently not absolutely necessary for a restoring element for generating a restoring force of elasticity to be present.
The holding means may be formed, in principle, by one or more treating or processing means of the machine, which follows/follow the roll changer in the path of the working web and which is/are considered to belong to the roll changer in such a design of the holding means for the purposes of the present invention. However, the holding means is preferably formed on the path of the working web in front of the first treating or processing means, which follows the pulling means according to the present invention in order to obtain a short web path between the pulling means and the holding means. It shall be ensured by the holding means that the stopped working web can indeed be pulled off from the working roll by means of the pulling means by a sufficient amount. The working web must be pulled out by at least such a length that the connection to the working web can be established. The beginning of the web of the reserve roll should preferably also be separated from the reserve roll by the pulling out. The holding means must therefore fix the web at least in the sense that the working web is not pulled out of the machine in the direction of the roll changer by means of the pulling means, while pulling off or pulling out of the working web from the working roll does not take place to a sufficient extent.
In a web-fed rotary printing press, the holding means may be formed especially by a pulling roller or a plurality of pulling rollers, which is/are arranged in the way of the working web in front of the first printing mechanism, especially by a draw-in mechanism for the printing mechanism or for a plurality of printing mechanisms. This also applies analogously to the corresponding means in other web-treating or -processing machines. For roll change during stoppage, such a pulling roller or the plurality of pulling rollers is/are fixed, i.e., the pulling roller or pulling rollers can be preferably blocked. If the coefficient of friction between the web and such a pulling roller or a plurality of pulling rollers is already sufficient for fixing the web, the holding means according to the present invention may be formed by a pulling means that is already present. However, a pressing element is arranged adjacent to a pulling element following the pulling means according to the present invention most closely such that the pressing element can be pressed against the pulling element in order to clamp and fix the web between the pulling element and the pressing element such that the web cannot be pulled in in the rearward direction by the action of the pulling means according to the present invention.
In a process according to the present invention for the automatic roll change during stoppage in a web-treating machine, at least the following operations are performed. The reserve roll is moved into a joining position. The reserve web, which is wound up into the reserve roll, is located in the joining position in parallel to and at a spaced location from the working web pulled into the machine, so that the reserve web will exactly overlap the working web in the case of its winding off. The working web is pressed in the joining position of the reserve roll to a beginning of the web of an outermost web layer of the reserve roll and is connected to this beginning of the web. The working web is fixed downstream of the beginning of the web of the reserve roll, preferably clamped such that it does not move or it does not move to a practically relevant extent in the longitudinal direction of the web under the effect of the pulling forces acting for the roll change at the site of the fixation. The fixation is preferably performed before the connection is established. The fixation may be performed after the working web is pressed onto the reserve roll or preferably before the pressing on. The case in which the working web had already been fixed before the reserve roll assumed the joining position shall not be excluded, either. After the connection is established, a pulling force is applied to the fixed working web at a point between the beginning of the web of the reserve roll and the point of fixation, and the working web is pulled from the working roll as a result. Finally, the working web is severed at a point between the working roll and the beginning of the web of the reserve roll.
The unwinding of the working web from the working roll is controlled during the pulling out operation from the working roll, e.g., by the working roll being driven by a rotating drive motor in a manner coordinated with the pulling-out speed of the pulling means according to the present invention. Instead of by a preferably regulated drive of the working roll, which is coordinated in this sense, the controlled unwinding may advantageously also be brought about by the controlled braking of the working roll in order to set a favorable web tension for the pulling out.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.